This invention relates to a torque and rotating speed sensor for detecting both torque of a rotating shaft and rotating speed (rpm) of the rotating shaft.
In an automatic transmission in a car employing an torque converter, speed change, line pressure, and the like have been controlled according to an rpm (a number of rotation) of an engine or throttle valve opening. In addition, it is known that with the line pressure control according to the torque of a turbine shaft the automatic transmission effectively displays a feature.
Also a known technique is that a magnetic sensor is used for directly detecting the torque of a rotating shaft such as the turbine shaft. In the sensor, a pair of magnetic recording parts respectively to which a location signal in a circumferential direction of the rotating shaft is to be recorded are provided on the rotating shaft, being axially spaced, and a pair of magnetic heads for recording and reproducing the location signal are respectively opposed to the respective magnetic recording parts. A quantity of torsion of the rotating shaft is measured based on a phase shift of the location signals to be reproduced by each magnetic head so as to obtain the torque according to the torsion quantity (refer to Japanese Patent Publication Gazette No55-34369).
Accordingly, it may devised that the automatic transmission perfoms controls based on the torque of the turbine shaft detected by the magnetic sensor. While, in the automatic transmission control, in addition to the torque of the turbine shaft, rpm of an engine is required to separately detect for speed change control and torque-down control. The rpm of the engine can be obtained according to the detected rpm of the turbine shaft.
In such the case where torque and rotating speed are detected only from the single rotating shaft, however, each sensor for detecting each is required. Further, a space for arranging each signal detecting means for the sensors is required on the rotating shaft, which leads to an oversized, heavy, expensive automatic transmission. As to detection of the rpm, in a method of detecting the rpm from a frequency by writing an optical mark circumferentially on a surface of the rotating shaft and scanning the mark, a frequency for writing the optical mark cannot be made high, which means no improvement in detecting an accurate rpm.
An object of the present invention is to provide a torque and rotating speed sensor for simply, accurately detecting both torque and rpm without increases in size and weight and with low cost.
Another object of the present invention is to provide a torque and rotating speed sensor for simply, accurately detecting the rotating speed at any time of high and low rpm of the rotating shaft.
Another object of the present invention is to provide a torque and rotating speed sensor for accurately detecting torque and rpm of the turbine shaft in an automatic transmission.
Further object of the present invention is to realize an ideal line pressure control in the automatic transmission.